Theses and Dissertations

Title: Influence of nitrogen fertilizer upon standing crop of zooplankton in ponds stocked with different numbers of Tilapia mossambica Peters

Name: Varikul, Vanich

Degree: MS

Chair: Dr. John S. Dendy

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1965

Pages: 49

Keywords: Nitrogen Fertilizer,Zooplankton,Tilapia mossambica.


The influence of nitrogen as an ingredient of inorganic fertilizer for fish ponds was investigated by using standing crop of plankton and gain in weight of fish as parameters of productivity. Twelve 0.25-acre ponds of the Auburn University Agricultural Experiment Station, Auburn, Alabama, were used. Of these, 4 received no fertilization, 4 received (N-P2O5-K2O) 0-8-2 and 4 received 8-8-2 fertilization. Ponds that received each fertilizer treatment were stocked with Tilapia mossambica Peters at rates of 2,000, 4,000, 6,000, and 8,000 per acre. Quantities of plankton were evaluated by dry weights in grams per liter of samples and by estimated total volumes of dominant zooplankters in mm3 per liter of samples. Estimations of volumes were based on volumes of clay models of the different organisms. The dry weights of plankton and the gains in weights of fish were greater in fertilized ponds than in unfertilized ponds, but there were no such differences between ponds that received nitrogenous and non-nitrogenous fertilizers. The results obtained from the estimated volumes of various zooplankters did not necessarily agree with the other factors. There were greater volumes of Cyclopidae in fertilized than in unfertilized ponds, but in ponds fertilized with nitrogenous (8-8-2) and non-nitrogenous (0-8-2) fertilizers volumes were approximately the same. Bosminids were more abundant in unfertilized than in fertilized ponds. There was no difference between estimated volumes of Diaptomidae in fertilized and unfertilized ponds. The volumes of nauplii, Sididae and Daphnidae, and Rotifers were not unformly different in fertilized and unfertilized ponds. The producitons of fish determined upon draining the ponds were greater in fertilized (8-8-2) and (0-8-2) ponds than i unfertilized (0-0-0) ponds, but the difference in productions of fish between (8-8-2) and (0-8-2) ponds was not significant. The differences in productions of fish due to the rates of stocking in fertilized ponds were significant, but productions due to the rates of stocking in unfertilized ponds were not significantly different. In fertilized ponds the stocking rates of 2,000, 4,000, 6,000, and 8,000 per acre resulted in production rates of 322, 621, 679 and 748 pounds per acre respectively, while in unfertilized ponds, the production was 202, 231, 179 and 254 pounds per acre respectively.

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